I've had many conversations recently about shooting a SAUM where limitations on muzzle energy becomes a bit of a concern, or certainly leading to uncharged territory. I will be shooting on a range next year that has a 4500 Joule limit, meaning that a 180 Berger cannot be driven more than roughly 2880 fps. Although I've shot around this mark, with good success, my fear is that even just a little temperature variation can cause me to be over. I am interested insome opinions from others to the best course of action for a situation like this.

So some data, currently shooting 32" barrel with 2209 and Sierra 183gn... This would make the limit even lower to about 2830. Given this, my options as I see it are:

1. Try to find a lower node.... does anyone have any ideas if one exists in the SAUM down low ? This would be like driving a Ferrari in second gear and on diesel.... 2. Reduce barrel length to reduce velocity with the same/similar pressure pulse.3. Change the projectile to something lighter (say 162 ELD / 168 Berger) to keep the velocity up, but would need to consider BC for longer ranges4. Change to a 284 which shoot 183gn Sierra's very comfortably at the lower velocities.

Hi Albert. Now as I believe u refer to shooting at Trentham and u will be shooting in the F Open class against me then maybe you could consider the 6br ? Conditions at Trentham are always very kind with very little wind there.

I jest. But seriously you could make contact with the NRANZ and see what they suggest. But all said and done you're operating right on the borderline and a hot day could put u over the range limit, as you're well aware. But remember too our "hot" is way different to yours.

Personally mate I'd suggest just running with a lighter bullet, presuming that's a much easier solution than a cartridge change ? As with any range anywhere surely some good condition reading and an accurate rifle will have u in good stead, as opposed to just pure horsepower and reduced wind drift numbers.

The wind at Trentham can be nasty that's for sure but seems no one told Bob Pedersen that because he totally dominated the F Open Nationals here in January. Regards Rob Kerridge.

Have you thought of trying ar2213sc with your current bullet. Slower burning may allow a longer node, possibly starting a little lower in velocity than where your current node is, while achieving good case fill still.

There WILL be lower nodes, and with the excellent ballistics of the 183 you'll still have very good performance in the wind. Even if you have to drop 150 fps from your favoured velocity, the effect of a 2mph (typical) wind change will only be slightly more, e.g. at 1000yd, less than an inch on the target. Plus you'll have less recoil, less fouling, and lower barrel temperature i.e. improved accuracy. Velocity is overrated as a wind reading advantage - BC is more important, and overall, accuracy even more important.

Velocity seduces us all, me included. This post is as much for my benefit as yours .

Ifhow Many rounds through the barrel? If it is getting on a bit then rechambering back to 28” or so will knock some speed off, while still keeping enough pressure to keep your ES/SD down for the longs. I would be sticking with 2209 and picking bullets which shoot well jammed to keep pressure u if you were staying with a SAUM. Better still would be to buy a 308 bolt body and run it as a 284.

I reckon these range energy limits are complete BS.. Everyone knows these regulations exist but not once have i seen them enforced or anybody tested..

Albert,

As you know I run a saum.. I run a 28" barrel because of these energy limits.. 178gr pills are running 2915fps, (which is under the 3500ft/lb energy rating at most ranges) unfortunately I've run out of them.. I did however work a load up with 162gr ELD-M but where they shot accurately in my rifle was way over the energy limit so I haven't bothered with them..Just do what I did and build a .308

Cheers

Alan

Last edited by Wal86 on Mon Oct 30, 2017 4:39 pm, edited 2 times in total.

Wal86 wrote:Unfortunately until these range energy restrictions are enforced, some members will continue to shoot outside these range restrictions.. It would be good to see a Labradar come out at shoots